Levels of trace amounts of materials in solution with solvents, or suspended in liquids, having a relatively high boiling point are determined by filtering the materials from the higher boiling point solvents. In an additional step, the materials are placed into solution by means of a solvent having a lower boiling point. The lower boiling point solvent is then eliminated, and the quantity of material determined, such as by weighing the material.
Typically, levels of trace amounts of materials which are in solution in, or are suspended in, water are determined by this method. The materials are removed from the water by means of a filter. The filter may be selected as having an affinity for the materials to be removed. A solvent having a greater affinity for the materials than the filter, and having a relatively low boiling point, is used to remove the materials from the filter for collection and subsequent analysis or processing. The materials may be hydrocarbons, such as oil and grease, which are suspended in water.
More specifically, the sample is placed through the filter or other extraction medium, which extracts the material from the water. Typically, this has been done by applying a vacuum to a flask, and positioning a filter or extraction medium over the opening to the flask. The vacuum pulls the sample through the filter or extraction medium, and collects the material, while allowing the water to fall within the flask. The water is discarded and the filter or extraction medium is retained for further processing.
Such further processing requires manually handling the filtration apparatus that houses the filter or extraction medium, and again placing the filter or extraction medium adjacent to the opening of a flask. A solvent having a relatively low boiling point, and which is selected to extract the hydrocarbon from the filter or extraction medium, is used to extract the material from the filter. The solvent is passed through the filter and into the flask. The collected solvent, with the material in solution, is then available for further analysis or processing.
It is desirable to pass the solvent through an additional step to remove residual water. A drying material, such as sodium sulfate, may be used to dry the material. The drying material may be contained in a cartridge which is attached to the system.
In the prior art, the process described above is performed in three separate and distinct steps, each of which requires significant handling. A first flask must be set up before filtration or extraction of the material from the sample. A second flask is set up for the introduction of the solvent to the material. A third apparatus is set up to dry the solvent.
This process is time consuming, but further, requires undesired handling of the filter or extraction medium, and the extraction apparatus, which may introduce contamination into the process. Further, the method requires handling of solvents, which may be hazardous, especially in light of the use of solvents having low boiling points. Significant ventilation may be necessary for the solvents in the prior art method. This is especially true if the solvent is to be transported or poured, such as pouring the solvent through the drying material. Hazardous evaporation of the solvent continues to occur, resulting in the requirement of significant ventilation.